Field of the Invention
The present invention relates to a ventilated seat element. More particularly, the present invention relates to passive ventilated vehicular seat element.
Description of the Prior Art
Isocyanate-based polymers are known in the art. Generally, those of skill in the art understand isocyanate-based polymers to be polyurethanes, polyureas, polyisocyanurates and mixtures thereof.
It is also known in the art to produce foamed isocyanate-based polymers. Indeed, one of the advantages of isocyanate-based polymers compared to other polymer systems is that polymerization and foaming can occur in situ. This results in the ability to mould the polymer while it is forming and expanding.
One of the conventional ways to produce a polyurethane foam is known as the “one-shot” technique. In this technique, the isocyanate, a suitable polyol, a catalyst, water (which acts as a reactive “blowing” agent and can optionally be supplemented with one or more physical blowing agents) and other additives are mixed together at once using, for example, impingement mixing (e.g. high pressure). Generally, if one were to produce a polyurea, the polyol would be replaced with a suitable polyamine. A polyisocyanurate may result from cyclotrimerization of the isocyanate component. Urethane modified polyureas or polyisocyanurates are known in the art. In either scenario, the reactants would be intimately mixed very quickly using a suitable mixing technique.
Another technique for producing foamed isocyanate-based polymers is known as the “prepolymer” technique. In this technique, a prepolymer is produced by reacting polyol and isocyanate (in the case of a polyurethane) in an inert atmosphere to form a liquid polymer terminated with reactive groups (e.g. isocyanates). To produce the foamed polymer, the prepolymer is thoroughly mixed with a lower molecular weight polyol (in the case of producing a polyurethane) or a polyamine (in the case of producing a modified polyurea) in the presence of a curing agent and other additives, as needed.
As is known in the art, foamed isocyanate-based polymers are commonly used to produce parts used in vehicles. These include vehicular seats. A typical vehicular seat comprises a seat bottom and a seat back.
In recent years it has become conventional to employ ventilated seats in automobiles, particulary active ventilated seats.
In the production of an active ventilated seat, particularly one for use in an automobile, it is known in the art, for example, to incorporate heating elements in the seat which are then connected to a power supply and a control system to allow the occupant of the automobile to turn on or turn off the heating elements for occupant convenience in colder climates. In the past, this has been achieved by adhering to the seating element some form of resistant heating system.
This prior art approach is disadvantageous for a number of reasons.
First, since the heat provided from the heating element is somewhat localized, it must be used over substantially the entire surface of the seat which, in many cases, has a deleterious affect on the comfort properties of the seat.
Second, since the heating system is resistive, there is a risk that some of the heat emitted will penetrate the seat rather than emit the seat toward the occupant. This can lead to premature discolouration and wear of the seat component and, in certain circumstances, may present a safety risk. Alternatively, an intermediate projective layer between the heating element and the seat pad could be used, but this adds extra expense and weight to the seat.
Third, the prior system simply provides a heated seat which is of little use to an occupant who seeks improved convenience in a warmer climate.
Fourth, this prior system is not designed to address the humidity microclimate that exists between the occupant of the seat and the seat surface. This creates occupant discomfort regardless of the temperature control achieved using either prior art approach.
Another approach has involved molding into the seat element a conduit system that is connected to a motor that forces air, particularly heated and/or cooled air, through the conduit system. In some cases, the forced air temperature can be regulated to provide what is known in the art as a climate control seat.
Both of the prior art approaches described above add weight cost to the production of the vehicular seat. Further, given the heterogeneous composition of the vehicular seats made using these prior art approaches, recyclability becomes an increased challenge.
The prior art has attempted to address various of these problems by providing so-called passively ventilated vehicular seats.
For example, U.S. Pat. No. 7,070,232 [Minegishi et al. (Minegishi)] teaches a so-called breathable seat that comprises a seat foam body formed of urethane foam and a three-dimensional network cushion body incorporated in that region of the seat body which bears a user's body weight, a seat cover having breathability and a seat pan. The cushion body is formed from a large number of continuous linear elements of thermal plastic resin. The linear elements are looped windingly so that their respective contact portions are fused together. The seat body is formed having so-called venting holes that pass through the urethane foam in its thickness direction. The venting holes communicate with the cushion body and apertures of the pan frame. The seat cover envelopes the seat body and the cushion body. A disadvantage with the approach taught by Minegishi is that it requires the use of two separate elements to achieve the so-called breathable seat. Specifically, the urethane seat body must be configured to receive a cushion body which is not a foam material. This adds to the cost and complexity of producing a seat body and also suffers from the above-mentioned difficulties with recyclability of the seat body when it is discarded after use.
German patent DE100 02 464 C1 teaches a motor vehicle seat having a foamed core and at least one air duct extending in the core, an air-permeable seat cover, below which are air distribution layer is arranged made of material which is air permeable on all sides and with an air impermeable dividing layer between the foamed core and the air distribution layer. The core is foamed in situ and is encased on all sides by an air impermeable foam layer and the air duct is formed by inserting a core tube extending from the impermeable foam rear layer to the air impermeable front dividing layer. The seat described in this German patent publication suffers from the same difficulties as that described above for Minegishi, namely that the seat is expensive and complex to manufacture and is difficult to recycle after the product is discarded.
U.S. Pat. No. 5,226,188[Liou] teaches a ventilated foam cushion comprising a pad with an upper surface having a plurality of through holes a seat portion having a recess for receiving the pad, the seat portion having a plurality of ventilation holes. When a user sits on the cushion, the pad and the seat will be deformed thereby causing the air therein to eject upwardly to blow off heat evolved from the user. The problem with the approach in Liou is that an occupant of the seat will effectively block the through holes in the upper surface of the pad thereby effectively nullifying the circulatory effects depicted in the drawings of Liou. Thus, the temperature and humidity microclimate at the interface of the use and the upper surface of the cushion is not improved in an appreciable way. A further disadvantage of the approach in Liou is that is requires the presence of separate elements which must be combined to produce the cushion (i.e., the upper pad and the seat portion having a recess to receive the upper pad).
United States patent application publication number U.S. 2011/0169318 [Lem et al. (Lem)] teaches a passively air-conditioned motor vehicle seat comprising a breathable seat cover which has ventilation channels extending in the thickness direction. Each ventilation channel has at least one valve element for preventing the return flow of air in the direction from the B-surface of the seat to the A-surface of the seat. In a preferred embodiment, the valve element is constructed from the same material as the seat body. The approach in Lem suffers from the disadvantages as described above with respect to Liou, namely that the temperature and humidity microclimate at the interface of the seat occupant and the A-surface of the seat is not improved appreciably.
United States patent publication number U.S. 2011/0241404[Di Giusto et al. (Di Giusto)] teaches a vehicle supporting body having a padding which has a honeycomb body of elastic material and is covered with upholstery permeable to air and defining a user supporting surface. The cells of the honeycomb body extend along axis crosswise to the supporting surface and are open at the end. In use, there is a variance in volume of air in response to offsetting movement of the user on the seat supporting body. The seat supporting body comprises a number of connecting cells that are purportedly opened and closed automatically by valves in response to compression and decompression of the air in the cells—see FIGS. 2A-2D. The approach in Di Giusto suffers from the same disadvantages as described above with respect to Lem and Liou, namely that the temperature and humidity microclimate at the interface of the occupant of the seat and the A-surface of the seat is not improved appreciably. In addition, the approach in Di Giusto suffers from the disadvantages described above with respect to Minegishi, namely that the construction requires a number of heterogeneous elements which increases the cost and complexity of producing the seat and raises challenges with respect to recyclability.
Given all of the above disadvantages of the prior art, it would be desirable to have a passively ventilated seat element which is relatively inexpensive to produce and provides an improvement in the interface between the occupant of the ventilated seat element and the A-surface of that element. It would also be advantageous to have such a seat element which was relatively easy to recycle.